The present invention relates to a dynamic band allocation system for use in a network formed by connecting a plurality of multiplexing devices with digital private lines, for example, super digital interface (SD-I) lines.
Further, the present invention relates to a dynamic band allocation system which enables, in the above-mentioned network, dividing of the channels of the SD-I line into a sub-rate multiplex band, which is a band for on-demand connection and/or a reserved connection and/or a fixed allocation connection and/or a fixed connection, and a bit multiplex band, which is a band for a fixed allocation connection and/or a fixed connection. As for the on-demand connection and/or the reserved connection and/or the fixed allocation connection, a trunk or a channel is selected actively (corresponding to every call) for connection to the opposing multiplexing device, and the on-demand connection and/or the reserved connection and/or the fixed allocation connection is divided into a voice band and a data band, wherein the ratio of division between the voice band and the data band can each be changed according to the traffic of each.
The structure of the network formed by connecting a plurality of multiplexing devices by an SD-I line is explained using FIG. 7. The network is formed, for example, by connecting a multiplexing device 10A, which is connected to terminal devices 30-1A through 30-5A, and a multiplexing device 10B, which is connected to terminal devices 30-1B through 30-5B, by an SD-I line 20. The multiplexing devices are not limited to two opposing devices, but more than three devices could be connected as a network. Each multiplexing device 10 includes a call path switch 11, a central processing unit 12, a memory device 13, a control bus 14 and a number of trunks 15.
In a network formed by connecting a plurality of such multiplexing devices by the SD-I line 20, the trunks 15 and the channels of the line 20 are set to be connected in advance by a fixed mode in each multiplexing device 10. Therefore, in the prior art, the dynamic band allocation system for dynamically allocating the band to the channel on the SD-I line was performed by selecting and connecting a trunk 15 which corresponds to the signaling speed of the terminal device 30 when the signal was originated from the terminal device 30.
That is, when a call was originated from a terminal device, such as a telephone machine, 30-3A having a signaling speed of 8 kbps, a trunk 15-1A connected to channel ch1 having a signaling speed of 8 Kbps might be selected for connection. Next, when another terminal device 30-2A having a signaling speed of 8 kbps originates a call, a trunk 15-2A connected to channel ch2 having a signaling speed of 8 kbps might be selected for connection. Further, when a further terminal device (telephone machine) 30-1A having a signaling speed of 8 kbps originates a call, a trunk 15-3A connected to channel ch3 having a signaling speed of 8 kbps might be seized for connection.
On the other hand, when a terminal device 30-4A having a signaling speed of 20 kbps originates a call, a trunk 15-7A connected to channels ch6 through, each having a signaling speed of 8 kbps, is seized for connection.
Further, a call originated from a terminal device 30-5A having a signaling speed of 12 kbps is connected to a selected trunk 15-15A which is connected to two channels, ch15 and ch16, each having a signaling speed of 8 kbps.